summaryrefslogtreecommitdiff
path: root/src
diff options
context:
space:
mode:
Diffstat (limited to 'src')
-rw-r--r--src/lib/hash/adler32.go26
-rw-r--r--src/lib/hash/crc32.go19
-rw-r--r--src/lib/hash/md5.go9
-rw-r--r--src/lib/hash/sha1.go9
4 files changed, 46 insertions, 17 deletions
diff --git a/src/lib/hash/adler32.go b/src/lib/hash/adler32.go
index 07818992e..e8876eba3 100644
--- a/src/lib/hash/adler32.go
+++ b/src/lib/hash/adler32.go
@@ -2,41 +2,44 @@
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
-// Adler-32 checksum.
+// This package implements the Adler-32 checksum.
// Defined in RFC 1950:
// Adler-32 is composed of two sums accumulated per byte: s1 is
// the sum of all bytes, s2 is the sum of all s1 values. Both sums
// are done modulo 65521. s1 is initialized to 1, s2 to zero. The
// Adler-32 checksum is stored as s2*65536 + s1 in most-
// significant-byte first (network) order.
-
package adler32
import "os"
+// Digest represents the partial evaluation of a checksum.
type Digest struct {
a, b uint32;
n int;
}
const (
- _Mod = 65521;
- _MaxIter = 5552; // max mod-free iterations before would overflow uint32
+ mod = 65521;
+ maxIter = 5552; // max mod-free iterations before would overflow uint32
)
+// NewDigest creates a new Digest.
func NewDigest() *Digest {
return &Digest{1, 0, 0};
}
+// Write updates the Digest with the incremental checksum generated by p.
+// It returns the number of bytes written; err is always nil.
func (d *Digest) Write(p []byte) (nn int, err *os.Error) {
a, b, n := d.a, d.b, d.n;
for i := 0; i < len(p); i++ {
a += uint32(p[i]);
b += a;
n++;
- if n == _MaxIter {
- a %= _Mod;
- b %= _Mod;
+ if n == maxIter {
+ a %= mod;
+ b %= mod;
n = 0;
}
}
@@ -44,15 +47,18 @@ func (d *Digest) Write(p []byte) (nn int, err *os.Error) {
return len(p), nil
}
+// Sum32 returns the 32-bit Adler-32 checksum of the data written to the Digest.
func (d *Digest) Sum32() uint32 {
a, b := d.a, d.b;
- if a >= _Mod || b >= _Mod {
- a %= _Mod;
- b %= _Mod;
+ if a >= mod || b >= mod {
+ a %= mod;
+ b %= mod;
}
return b<<16 | a;
}
+// Sum returns the 32-bit Adler-32 checksum of the data written to the Digest
+// in the form of an array of 4 bytes in big-endian order.
func (d *Digest) Sum() []byte {
p := make([]byte, 4);
s := d.Sum32();
diff --git a/src/lib/hash/crc32.go b/src/lib/hash/crc32.go
index 7bfca39d3..eb1dff3ba 100644
--- a/src/lib/hash/crc32.go
+++ b/src/lib/hash/crc32.go
@@ -2,13 +2,13 @@
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
-// CRC-32 checksum.
-// http://en.wikipedia.org/wiki/Cyclic_redundancy_check for links
-
+// This package implements the 32-bit cyclic redundancy check, or CRC-32, checksum.
+// See http://en.wikipedia.org/wiki/Cyclic_redundancy_check for information.
package crc32
import "os"
+// Predefined polynomials.
const (
// Far and away the most common CRC-32 polynomial.
// Used by ethernet (IEEE 802.3), v.42, fddi, gzip, zip, png, mpeg-2, ...
@@ -25,9 +25,11 @@ const (
Koopman = 0xeb31d82e;
)
+// Table is a 256-word table representing the polynomial for efficient processing.
// TODO(rsc): Change to [256]uint32 once 6g can handle it.
type Table []uint32
+// MakeTable returns the Table constructed from the specified polynomial.
func MakeTable(poly uint32) Table {
t := make(Table, 256);
for i := 0; i < 256; i++ {
@@ -44,21 +46,29 @@ func MakeTable(poly uint32) Table {
return t;
}
+// IEEETable is the table for the IEEE polynomial.
var IEEETable = MakeTable(IEEE);
+// Digest represents the partial evaluation of a checksum.
type Digest struct {
crc uint32;
tab Table;
}
+// NewDigest creates a new Digest for the checksum based on
+// the polynomial represented by the Table.
func NewDigest(tab Table) *Digest {
return &Digest{0, tab};
}
+// NewIEEEDigest creates a new Digest for the checksum based on
+// the IEEE polynomial.
func NewIEEEDigest() *Digest {
return NewDigest(IEEETable);
}
+// Write updates the Digest with the incremental checksum generated by p.
+// It returns the number of bytes written; err is always nil.
func (d *Digest) Write(p []byte) (n int, err *os.Error) {
crc := d.crc ^ 0xFFFFFFFF;
tab := d.tab;
@@ -69,10 +79,13 @@ func (d *Digest) Write(p []byte) (n int, err *os.Error) {
return len(p), nil;
}
+// Sum32 returns the CRC-32 checksum of the data written to the Digest.
func (d *Digest) Sum32() uint32 {
return d.crc
}
+// Sum returns the CRC-32 checksum of the data written to the Digest
+// in the form of an array of 4 bytes in big-endian order.
func (d *Digest) Sum() []byte {
p := make([]byte, 4);
s := d.Sum32();
diff --git a/src/lib/hash/md5.go b/src/lib/hash/md5.go
index 98dae6f83..ab3201ffb 100644
--- a/src/lib/hash/md5.go
+++ b/src/lib/hash/md5.go
@@ -2,8 +2,7 @@
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
-// MD5 hash algorithm. See RFC 1321.
-
+// This package implements the MD5 hash algorithm as defined in RFC 1321.
package md5
import "os"
@@ -17,6 +16,7 @@ const (
_Init3 = 0x10325476;
)
+// Digest represents the partial evaluation of a checksum.
type Digest struct {
s [4]uint32;
x [_Chunk]byte;
@@ -24,6 +24,7 @@ type Digest struct {
len uint64;
}
+// NewDigest creates a new Digest.
func NewDigest() *Digest {
d := new(Digest);
d.s[0] = _Init0;
@@ -35,6 +36,8 @@ func NewDigest() *Digest {
func _Block(dig *Digest, p []byte) int
+// Write updates the Digest with the incremental checksum generated by p.
+// It returns the number of bytes written; err is always nil.
func (d *Digest) Write(p []byte) (nn int, err *os.Error) {
nn = len(p);
d.len += uint64(nn);
@@ -64,6 +67,8 @@ func (d *Digest) Write(p []byte) (nn int, err *os.Error) {
return;
}
+// Sum returns the MD5 checksum of the data written to the Digest
+// in the form of an array of 16 bytes in big-endian order.
func (d *Digest) Sum() []byte {
// Padding. Add a 1 bit and 0 bits until 56 bytes mod 64.
len := d.len;
diff --git a/src/lib/hash/sha1.go b/src/lib/hash/sha1.go
index dab477cd4..0bf284ef1 100644
--- a/src/lib/hash/sha1.go
+++ b/src/lib/hash/sha1.go
@@ -2,8 +2,7 @@
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
-// SHA1 hash algorithm. See RFC 3174.
-
+// This package implements the SHA1 hash algorithm as defined in RFC 3174.
package sha1
import "os"
@@ -18,6 +17,7 @@ const (
_Init4 = 0xC3D2E1F0;
)
+// Digest represents the partial evaluation of a checksum.
type Digest struct {
h [5]uint32;
x [_Chunk]byte;
@@ -25,6 +25,7 @@ type Digest struct {
len uint64;
}
+// NewDigest creates a new Digest.
func NewDigest() *Digest {
d := new(Digest);
d.h[0] = _Init0;
@@ -37,6 +38,8 @@ func NewDigest() *Digest {
func _Block(dig *Digest, p []byte) int
+// Write updates the Digest with the incremental checksum generated by p.
+// It returns the number of bytes written; err is always nil.
func (d *Digest) Write(p []byte) (nn int, err *os.Error) {
nn = len(p);
d.len += uint64(nn);
@@ -66,6 +69,8 @@ func (d *Digest) Write(p []byte) (nn int, err *os.Error) {
return;
}
+// Sum returns the SHA-1 checksum of the data written to the Digest
+// in the form of an array of 20 bytes in big-endian order.
func (d *Digest) Sum() []byte {
// Padding. Add a 1 bit and 0 bits until 56 bytes mod 64.
len := d.len;
generated by cgit v1.2.3 (git 2.39.1) at 2025-05-09 16:00:32 +0000